Heated Oxygen Sensor (Ho2S): Inspection

1. Disconnect the oxygen sensor connector, and measure the resistance between terminal 3 and terminal 4.

   Standard value 

   Fig 1: HO2S Temperature/Resistance Table

   Courtesy of HYUNDAI MOTOR CO.
   Fig 2: Locating HO2S

   Courtesy of HYUNDAI MOTOR CO.
2. Replace the oxygen sensor if there is a malfunction.
3. Apply battery voltage directly between terminal 3 and terminal 4.
   NOTE: Be careful when applying the voltage. Damage will result if terminals 1 and 2 are connected to any voltage.
4. Connect a high-impedance digital-type volt meter between terminal 1 and terminal 2.
   Fig 3: Identifying Front & Rear HO2S Connector Terminals

   Courtesy of HYUNDAI MOTOR CO.
5. While repeatedly racing the engine, measure the oxygen sensor output voltage.
   Fig 4: HO2S Voltage/Resistance Table

   Courtesy of HYUNDAI MOTOR CO.
   Fig 5: HO2S Rich/Lean Graph

   Courtesy of HYUNDAI MOTOR CO.
   Fig 6: HO2S Voltage Vs. Mixture Ratio Graph

   Courtesy of HYUNDAI MOTOR CO.
6. If there is a problem, there may be an oxygen sensor malfunction.

Tightening torque 

Heated oxygen sensor:

40~50 Nm (400~500 kg.cm, 29~36 lb.ft)

Fig 7: Heated oxygen sensor side connector (FRONT, REAR)

Courtesy of HYUNDAI MOTOR CO.